Brush holder



Dec. 2, 1941. J. D. MINER, JR

BRUSH HOLDER Filed June 8, 1940 INVENTOR WITNESSES: @AWM 71% Z.

hm Wm pm m J Patented Dec. 2, 1941 UNlTED STATES PATENT OFFICE inghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application June 8, 1940, Serial No. 339,430

(Cl. 1i1324) 8 Claims.

My invention relates to brushholders for dynamo-elcctric machines, and it has particular relation to brushholder-assemblies of the so-called cartridge type, comprising a tubular brushholder-member proper, usually of brass, having a rectangularly broached bore, for receiving a rectangularly sectioned brush which is pressed outwardly of the bore by means of a long, flexible, helical compression-spring, which is retained by an insulating cap which is screwed onto the end of the brushholder, and which is electrically connected to the brush either by means of the spring or by means of a so-called pigtail or flexible conductor.

Such brushholders have given trouble, in the past, from various causes, principal of which include the catching or hanging of one or more convolutions of the spring on shoulders or burrs Within the bore of the brushholder, and the winding up of the spring or the brush-pigtail, as the case may be, when the cap is screwed into place.

My invention relates to various improvements, in structural details, for overcoming the aforesaid and other disadvantages of the prior-art structures, as will be further understood from the following detailed description and claims, and from the accompanying drawing wherein:

Figure l is a view, partly in longitudinal section and partly in elevation, of a small motor embodying my invention;

Fig. 2 is a cross-sectional view of the brushholder-assembly, the section-plane being indicated by the lines 11-11 in Figs. 1 and 3;

Fig. 3 is a longitudinal sectional view of the brushholder-assembly, including a portion of the commutator cylinder with which it cooperates, the section-plane being indicated by the line III-III in Fig. 1;

Fig. 4 is a view, similar to Fig. 3, indicating a modification involving the use of a rotationpreventing terminal-washer and a flexible conductor or pigtail; and

Fig. 5 is a plan View of the terminal-washer of Fig. 4.

In Figure 1, I show my invention as being applied to a dynamo-electric machine in the form of a small motor, The particular motor which is illustrated embodies certain improvements in the housing and bearing-constructions which have nothing to do specifically with the brushholder improvements of my present invention, and which are specifically described and claimed in my copending application Serial No. 330,075, filed April 17, 1940, for Electric-motor constructions. The motor comprises a stator member 6 including a frame i, a rotor member 8 carrying a cylindrical commutator 9 or other rotating current-collecting member. The frame 1 carries two diametrically disposed brushholder-assemblies, one of which is shown at H in Fig. 1. Each brushholder-assembly includes a brush l2 which bears upon the surface of the commutator 9.

My improvements in the brushholder-assembly ll are shown in Figs. 2 to 5. The brushholderassembly comprises a tubular member l3 constituting the brushholder proper, made of brass or other metal, having a smooth bore M, which is angularly broached at four points [5 so as to provide a square or rectangularly shaped cross-section, running smoothly all of the way through the metal tube la. The central portion of the metal tube I3 is surrounded by an insulating sleeve I! which is tightly pressed onto the metal tube, and which consttiutes a seat for a supporting-means 49 which is illustrated as comprising a bracket surrounding the insulating sleeve l1 and secured to the motor-frame l by means of bent-over ears 9. The brushholder-assembly is thus held in its proper position by and within the motorirame 1, so that the center-line of the brushholder extends at substantially right angles to the surface of the commutator 9, it being understood that the brush l2 makes a current-collecting contact or engagement with the surface of the commutator 9.

The outer end of the brushholder tube l3, or the end furthest away from the commutator 9, is externally threaded, as indicated at 2|, so as to receive an insulating cap 23 which is threaded thereon, in order to close said end of the brushholder, and so as to hold in place, a long, flexible, helical, wire compression-spring 25. The motorframe 1 is provided with a perforation 26 through which the brushholder-cap 23 can be removed or assembled. The inner end of the brushholdertube l3, or the end closest to the commutator 9, is provided with an encircling groove 21 (Fig. 3) which receives a terminal-lead 28 (Fig. 1) which is engaged in said groove 21 by means of a garter-spring 29 (Fig. 1).

In accordance with my invention, it will thus be seen that I have provided means whereby the long, flexible, helical compression-spring 25 is disposed within an absolutely smooth bore or tubular spring-housing, by which I mean that the bore or housing which surrounds the spring is smooth in a longitudinal direction, considering longitudinally with respect to the tube l3, so that all of the convolutions of the spring are free to move axially with respect to the brushholder without the possibility of any convolution coming into contact with any roughness or edge upon which it could catch, if the spring or a convolution thereof, should become displaced laterally so as to touch the walls of the bore I4 or housing surrounding the spring. No previous cartridgetype brushholder-construction with which I am acquainted has been thus free of burrs or edges which might constitute obstructions on which the compression-spring could catch, such previous brushholders either having internal threads within the bore of the tube, or other obstructionmeans which would defeat the purpose of my smooth-bore construction.

In accordance with my invention, I further provide improved means for effecting a good electrical contact between the brush I2 and the metal tube I3, and thence to the terminal-lead 28, so as to avoid the rapid side-wear of the brush I2, which inevitably occurs whenever any material amount of current is conducted directly between the brush and the bore of the brushholder I3.

Thus, in Fig. 3, I utilize the spring 25 itself as the current-conductor, and to this end, I preferably make the spring out of a material having a considerably better electrical conductivity than steel or phosphor-bronze, a suitable high-conducting spring-material being an alloy of beryllium and copper. In order to make a good, reliable contact between the spring 25 and the metal tube I3, I provide the outer end of the spring, that is, the end furthest away from the brush I2, with an enlarged or large-diameter end-turn 3| which is clamped between the end of the metal tube I3 and the cap 23.

In order to prevent the screwing on of the cap 23 from causing a turning or rotation of the spring 25, and thus possibly catching the inner end of the spring on any roughness in the top surface of the brush I2, I may provide the enlarged outer end-turn 3I with a wire-extension 32 which is bent down in an axial direction, so as to slide axially or longitudinally in one of the broached angles I5; of the bore I4, so as to prevent the spring from rotating, and this bent spring-end 32 may extend long enough in a longitudinal direction, so that it engages its broached corner I5 before the threads of the cap 23 engage the threads 2| of the metal tube I3, so that the rotation-preventing means is in operation before the mechanic begins to turn the cap 23, in the process of assembling the mechanism.

In Figs. 4 and 5, I show a modification of my invention in a so-called shunted-brush construction, in which the spring 25 is shunted by means of a so-called pigtail 36 or flexible conductor which is attached at one end to the brush I2, and the other end of which is utilized to make engagement, in some way, with the metal tube I3. In accordance with this aspect of my invention, I preferably secure the free end of the pigtail 36 to a simple metal terminal-washer 3'! having a large-diameter flat portion 38 which is clamped between the cap 23 and the end of the metal tube I3, said terminal-washer also having bent-over side-portions 39 which engage within the broached corners I5 of the bore I4, and are long enough to prevent the rotation of the cap 23 from being transmitted to the metal terminal-washer 31. The spring 25, in this embodiment of my invention, abuts up against the inner side of the metal terminal-washer 37, where it may be centered by means of a cupshaped depression 40. The pigtail 36 is'centrally secured within said depression 40 in the metal terminal-washer 31. By this means, I not only prevent the rotation of the spring 25, when the cap 23 is screwed into place, but I also prevent the winding-up of the pigtail 36, which, if permitted to take place, might shorten the pigtail to such an extent that it might break or at least prevent the proper movement of the brush I 2.

While I have described my invention in two forms of embodiment which are now preferred by me, I wish it to be understood that such description is largely illustrative, as many changes may be made by those skilled in the art, by way of additions, substitutions, and omissions, without departing from the essential spirit of my invention, particularly in its broader aspects. I desire, therefore, that the appended claims shall be accorded the broadest construction consistent with their language.

I claim as my invention:

1. A dynamo-electric machine comprising a stator member, a frame therefor, a rotor member, a rotating current-collecting member carried by the rotor member, a brushholder insulatedly supported by and within said frame, and a contact-making brush movably carried by said brushholder and yieldably pressed against said rotating current-collecting member, characterized by said brushholder comprising a tubular metal member having a smooth, rectangularly broached bore extending lengthwise therethrough and having its outer end screw-threaded on the outside, an insulating sleeve secured on said tubular metal member around a portion thereof intermediate of its ends, a supportingmeans engaging said insulating sleeve for retaining the brushholder in position Within said frame, an insulating cap threaded to said screw-threaded end of said tubular metal member so as to close said end, said frame having a perforation through which said cap can be removed or assembled, a terminal lead connected to the outside of said tubular metal member near its inner end, said contact-making brush being. a rectangularly sectioned brush disposed within the bore of said tubular metal member at the inner end thereof and extending out from said inner end into contact-making engagement with said rotating current-collecting member, and a long, flexible, helical compression-spring disposed within the bore of said tubular metal member and having one of its ends pressing said brush outward of said bore and having its other end retained by said cap, the intervening portion of the bore of the tubular metal member constituting a smooth, unobstructing lateral guide for all of the convolutions of the spring so as to offer no roughness or edge upon which any convolution may catch as it moves in an axial direction within said bore, the other end of said spring having a backwardly bent wire-extension engaging in said rectangularly broached bore for preventing rotation of said spring.

2. A dynamo-electric machine comprising a stator member, a frame therefor, a rotor member, a rotating current-collecting member carried by the rotor member, a brushholder insulatedly supported by and within said frame, and a contact-making brush movably carried by said brushholder and yieldably pressed against said rotating current-collecting member, characterized by said brushholder comprising a tubular metal member having a smooth, angularly sectioned bore extending lengthwise therethrough and having its outer end screw-threaded on the outside; an insulating sleeve secured on said tubular member around a portion thereof intermediate of its ends, a supporting-means engaging said insulating sleeve for retaining the brushholder in position within said frame, an insulat ing cap threaded to said screw-threaded end of said tubular metal member so as to close said end, said frame having a perforation through which said cap can be removed or assembled, a terminal lead connected to the outside of said tubular metal member near its inner end, said contact-making brush being an angularly sectioned brush disposed within the bore of said tubular metal member at the inner end thereof and extending out from said inner end into contact-making engagement with said rotating current-collecting member, and a helical compression-spring disposed within the bore of said tubular metal member and having one of its ends abutting upon the end of the brush within said bore, said spring being of a material having a better conductivity than steel and having its outer end-convolution enlarged so as to be clamped between the end of said tubular metal member and said cap.

3. A dynamo-electric machine comprising a stator member, a frame therefor, a rotor member, a rotating current-collecting member carried by the rotor member, a brushholder insulatedly supported by and within said frame, and a contact-making brush movably carried by said brushholder and yieldably pressed against said rotating current-collecting member, characterized by said brushholder comp-rising a tubular metal member having a smooth, angularly sectioned bore extending lengthwise therethrough and having its outer end screw-threaded on the outside, an insulating sleeve secured on said tubular member around a portion thereof intermediate of its ends, a supporting-means engaging said insulating sleeve for retaining the brushholder in position within said frame, an insulating cap threaded to said screw-threaded end of said tubular metal member so as to close said end, said frame having a perforation through which said cap can be removed or assembled, a terminal lead connected to the outside of said tubular metal member near its inner end, said contact-making brush being an angularly sectioned brush disposed within the bore of said tubular metal member at the inner end thereof and extending out from said inner end into contact-making engagement, with said rotating current-collecting member, and a helical compression-spring disposed within the bore of said tubular metal member and having one of its ends pressing said brush outward of said bore and having its other end retained by said cap, said other end having a backwardly bent spring-wire extension engageable within an angle of said bore and slidable axially within said angle, at the capped end of said tubular metal member, for a sufiicient distance to substantially prevent the rotating movement of the cap from being transmitted to the spring while the cap is being screwed into place.

4. A brushholder assembly comprising a tubular metal member having a smooth, rectangularly broached bore extending lengthwise therethrough and having a first end screw-threaded on the outside, an insulating sleeve secured on said tubular metal member around a portion thereof intermediate of its ends, an insulating cap threaded to said screw-threaded end of said tubular metal member so as to close said end, a terminal lead connected to the outside of said tubular metal member near its second end, a rectanguiarly sectioned contact-making brush disposed within the bore of said tubular metal member at said second end and extending out from said second end, and a long, flexible, helical compression-spring disposed within the bore of said tubular metal member and having one of its ends pressing said brush outward of said bore and having its other end retained by said cap, the intervening portion of the bore of the tubular metal member constituting a smooth, unobstructing lateral guide for all of the convolutions of the spring so as to offer no roughness or edge upon which any convolution may catch as it moves in an axial direction within said bore, the other end of said spring having a backwardly bent wire-extension engaging in said rectangularly broached bore for preventing rotation of said spring.

5. A brushholder assembly comprising a tubular metal member having a smooth, angularly sectioned bore extending lengthwise therethrough and having a first end screw-threaded on the outside, an insulating sleeve secured on said tubular metal member around a portion thereof intermediate of its ends, an insulating cap threaded to said screw-threaded end of said tubular metal member so as to close said end, a terminal lead connected to the outside of said tubular metal member near its second end, an angularly sectioned contact-making brush disposed within the bore of said tubular metal member at said second end and extending out from said second end, and a helical compression-spring disposed Within the bore of said tubular metal member and having one of its ends abutting upon the end of the brush within said bore, said spring being of a material having a better conductivity than steel and having its outer end-convolution enlarged so as to be clamped between the end of said tubular metal member and said cap.

6. A brushholder assembly comprising a tubular metal member having a smooth, angularly sectioned bore extending lengthwise therethrough and having a first end screw-threaded on the outside, an insulating sleeve secured on said tubular metal member around a portion thereof intermediate of its ends, an insulating cap threaded to said screw-threaded end of said tubular metal member so as to close said end, a terminal lead connected to the outside of said tubular metal member near its second end, an angularly sectioned contact-making brush disposed within the bore of said tubular metal member at said second end and extending out from said second end, and a helical compression-spring disposed within the bore of said tubular metal member and having one of its ends pressing said brush outward of said bore and having its other end retained by said cap, said other end having a backwardly bent spring-wire extension engageable within an angle of said bore and slidable axially within said angle, at the capped end of said tubular metal member, for a sufficient distance to substantially prevent the rotating movement of the cap from being transmitted to the spring while the cap i being screwed into place.

7. A dynamo-electric machine comprising a stator member, a frame therefor, a rotor member, a rotating current-collecting member carried by the rotor member, a bushholder insulatedly supported by and within said frame, and a contactmaking brush movably carried by said brushholder and yieldably pressed against said rotating current-collecting member, characterized by said brushholder comprising a tubular metal member having a smooth bore extending lengthwise therethrough, an insulating sleeve secured on said tubular metal member around a portion thereof intermediate of its ends, a supportingmeans engaging said insulating sleeve for retaining the brushholder in position within said frame, an insulating cap covering the outer end of the tubular metal member and removably secured on the outside of said tubular metal member, a terminal lead electrically connected to said tubular metal member, said contact-making brush being disposed within the bore of said tubular metal member at the inner end thereof and extending out from said inner end into contactmaking engagement with said rotating currentcollecting member, and a helical compressionspring disposed within the bore of said tubular metal member and having one of its ends abutting upon the end of the brush within said bore, said spring being of a material having a better conductivity than steel and having its outer endconvolution enlarged so as to extend between the end of said tubular metal member and said cap.

8. A brushholder assembly comprising a tubular metal member having a smooth bore extending lengthwise therethrough, an insulating sleeve secured on said tubular metal member around a portion thereof intermediate of its ends, an insulating cap covering a first end of the tubular metal member and removably secured on the outside of said tubular metal member, a terminal lead electrically connected to said tubular metal member, a contact-making brush disposed within the bore of said tubular metal member at the second end thereof and extending out from said second end, and a helical compression-spring disposed within the bore of said tubular metal member and having one of its ends abutting upon the end of the brush within said bore, said spring being of a material having a better conductivity than steel and having its outer end-convolution enlarged so as to extend between the end of said tubular metal member and said cap.

JOHN D. MINER, JR. 

